[lkcd-devel] User space analysis using _just_ lcrash

[Bharata B R. <bh...@in...>]

Here is one more approach for user space analysis using lcrash :-)

While the 2 previous approaches generate a core file to be used by gdb, our
approach is to do preliminary analysis of the task using just lcrash. 
With this, some initial investigation can be done to identify suspected tasks
and perform a quick analysis in an overall system context. Thereafter if 
needed a more comprehensive analysis can be done by generating the core 
for the problem task(s). 

Currently our approach provides the following facilities
1. User memory view (currently, only non-swap memory, but should be possible
   to use the available swap dumping schemes to view the entire task memory)
2. Task symbol resolution, including the shared object symbols (symbol map
   files should be provided via symtab command)
3. User space backtrace (only if symbol info is available)
4. User data structures dump (if kerntypes info is available)
5. User code disassembly, including library code.

Here is an example of how the backtrace of a task looks in the
overall sytem context.
================================================================
STACK TRACE FOR TASK: 0xc2ae6000(test3)

 0 schedule+726 [0xc010f026]
 1 schedule_timeout+121 [0xc010ed09]
 2 sys_nanosleep+265 [0xc0118ab9]
 3 system_call+44 [0xc0106cec]
   ebx: bffff8f8   ecx: bffff8f8   edx: 40145bc0   esi: bffff8f8
   edi: 00010000   ebp: bffffaa8   eax: 000000a2   ds:  002b
   es:  002b       eip: 400d4a61   cs:  0023       eflags: 00000286
   esp: bffff8dc   ss:  002b

USER STACK TRACE:
 4 __nanosleep+17 [0x400d4a61]
 5 func+14 [0x804849e]
 6 main+52 [0x80484e4]
 7 __libc_start_main+139 [0x4003ce5b]
================================================================

I have a working version of the patch, but it needs a bit of cleanup
and testing before it becomes release-ready.

Looking forward for the comments/feedback on this approach.
-- 
Bharata B Rao,
IBM Linux Technology Center, IBM Software Lab, Bangalore, India.
Ph: 91-80-5044962(5262355 X-3962), Mail: bh...@in....